Okay, does anybodys monte carlo do this? When i put the blower on the voltage meter goes down slightly. When i push the button to put the windows up it goes down quite a bit, causes the interior lights to dim, and even changes the idle as if the car is going to die. Im assuming this isnt supposed to happen?

I tested my battery. Its a 850cca battery and is currently around 750 which is still a ton and more than enough to start the car etc. but its never been full.

To me it sounds exactly like a bad alternator. My car also shuts off while running when you disconnect the battery. Could thiss issue also be causing my intermittant rough idle possibly not getting enough juice to the fuel pump/injectors etc.?

 

I would never trust tht alternator nesting method, way to dangerous and could mess the car up

 

Idk how accurate autozones testing is. But they can test alts on the car. Keep in mind My car on stock electrical used to have the lights dim when I used the windows and turn the AC on as well.. I never paid any attention to the voltage gauge On the dash though, Most gauges like that are very delayed in terms of how quickly they adjust to voltage drop. Iv also had unsteady RPMs for a few years on my 3.4. It will drop way down 300-400 rpms then jump to 700 not really sure why.. when it does that the car becomes rough. But thats obviously only at idle

 

Sounds like a failing Diode in the alternator....

Its best to bench test an alternator...

I believe a bench test should prove the alternator is faulty.

An 850 cca battery should be at 850cca or just a tic under... generally should be at 12 volts!
CCA isn't always the way to check power on a battery...Its all about the voltage!
How old is the battery? are you running a system?
Battery life is generally 3 to 5 yrs...(Longer if...your lucky)
Could be a combination alternator and a battery issue...
It could possibly have a bad cell/Or its worn out ....I would have the battery load tested!

 

Disconnecting the battery while the car was running was an old test for the alternator. It is HIGHLY recommended NOT to do this on modern cars due to all the sensitive computer controlled electronics.

Regardless of the parts store bench test being good or bad (I went through it myself, the alt failed on one bench test, passed on 5 cycles at 3 different places and later passed at the place that failed it, but end result, I still believe it was bad). I recommend you remove the alt and bench test it.

It sounds pretty suspect that the alt is failing. Have the parts store run it 2-5 times and see how many times it fails....